Review: Delayed Internet Routing Convergence

The demand from the best effort network to provide better performance and
low latency is increasing as time critical application are being build to
work over TCP/IP protocol. These include service like VoIP and emerging
QoS standards which assume a well behaved internet infrastructure. But
unfortunately the current Internet infrastructure was not build keeping in
view the requirements of such application and thus has certain delays that
could affect the performance of such applications. These delays could be
from congestion or form routing convergence. This paper focus on carrying
out a measurement study of latencies introduced by internet path failure
and convergence properties of internet.

The focus of study has been convergence behavior of BGP4 deployed in
today’s internet. Author has also provided the result of affects that
internet failovers have on end-to-end network performance. The study is
based on the data collected from two years of internet converge
monitoring. Over the two years 250,000 faults were injected in a network
infrastructure build to carry out this study. The impacts of these faults
were measured by both active and passive monitoring using the machines
deployed at major US exchange points and log of all the BGP updates were
maintained. The analysis of the data shows that end-to-end performance is
greatly affected by inter-domain failover and the packet loss grows by the
factor of 30 and latency by a factor of 4 during convergence and the
delays are mostly due to unforeseen interaction of protocol timers with
specific router vendor implementation decisions.

The though that internet support effective inter-domain failover has been
invalidated and author has shown that delays introduced by internet
inter-domain path failovers averaged three minutes while some of them took
up to minutes to become stable. Another important contribution of the
paper is that if specific changes to vendor BGP implementation are
deployed, it would significantly improve internet convergence latencies.
Received on Thu Oct 12 2006 - 10:03:37 EDT